При внимательном рассмотрении строение кисти arms, as well as any other department of our musculoskeletal system, rather difficult. It consists of three main structures: bones, muscles and ligaments that hold the bones. In the hand there are three sections, namely: the wrist, fingers and pasterns.
In this article we will look at the brush in detail: the structure, muscles, joints of the hand. Let's start with a description of the bones in its different sections.
Wrist bones
Since the hands must perform fairly accurate andintricate movements, the structure of the bones of the hand is also extremely complex. In the wrist - 8 small bones of irregular shape, arranged in two rows. In the figure below you can see the structure of the brush of the right hand.
The proximal row forms the articular surface,convex to the radius. It includes the bones, if you count from the fifth to the thumb: pea-shaped, trihedral, semi-lunar and scaphoid. The next row is distal. It connects with the proximal joint of irregular shape. The distal row consists of four bones: trapezoidal, polygonal, capitate and hooky.
Metacarpus bones
This department consists of 5 tubular metacarpals.bones, also demonstrates the intricate structure of the hand. The skeleton of these tubular bones is complex. Each of them has a body, base and head. The metacarpal bone of the 1st finger is shorter than the others and is massive. The second metacarpal bone is the longest. The rest decreases in length with distance from the first and closer to the ulnar edge. The bases of the aforementioned carpus bones are articulated with the bones forming the wrist. The first and fifth metacarpal bones have bases with articular surfaces of the saddle shape, others are flat. Heads of metacarpal bones with articular surface (hemispherical), articulate with proximal digital phalanges.
Finger bones
Each finger, with the exception of the first, whichconsists of only two phalanges and has no middle, there are 3 phalanges: distal, proximal and middle (intermediate). The shortest - distal; proximal - the longest. There is a phalanx head at the distal end, and its base at the proximal end.
Sesamoid bones of the hand
В толще сухожилий, кроме указанных костей, есть sesamoid, located between the proximal phalanx of the thumb and its metacarpal bone. There are still unstable sesamoid bones. They are between the proximal phalanges of the fifth and second fingers and their metacarpal bones. Usually sesamoid bones are located on the palmar surface. But sometimes they can be found on the back. Pisiform bone also refers to the above species. Sesamoid bones and their processes increase the shoulder strength of the muscles attached to them.
We have examined the structure of the hand and the bones of the hand; we now turn to the ligamentous apparatus.
Wrist joint
It consists of a radius and bones.proximal wrist: trihedral, lunate and scaphoid. The ulna is supplemented by the articular disc and does not reach the wrist. The main role in the formation of the elbow joint is the ulna. Then as the radiocarpal - ray. The wrist joint is ellipsoid in shape. There are possible abduction, adduction of the hand, flexion and extension. A small passive rotational movement (10-12 degrees) is also possible in this joint, but this is due to the elasticity of the articular cartilage. Through the soft tissue it is easy to detect the gap of the wrist joint, which is palpable from the elbow and radial sides. From the ulna, one can grope between the triangular bone and the head of the ulna. On the radial side there is a gap between the navicular bone and the lateral styloid process.
Движения лучезапястного сустава тесно связаны с the work of the median wrist joint located between the distal and proximal rows. The surface of his complex, irregular shape. With flexion and extension, the volume of mobility reaches 85 degrees. Bringing the hand in the above-mentioned joint reaches 40 degrees, the lead is 20. The wrist joint can circulate, i.e. circular motion.
This joint is reinforced by numerous ligaments.They are located between the individual bones, as well as on the lateral, medial, dorsal and palmar surfaces of the wrist. Collateral ligaments (radial and ulnar) play the most important role. On the ulnar and radial sides between the bone elevations there is a flexor retainer - a special ligament. In fact, it does not apply to the joints of the hand, being a thickening of the fascia. The flexor retainer converts the wrist groove into a channel in which the median nerve and the flexor tendons of the fingers pass. Continue to describe the anatomical structure of the hand.
Carpometacarpal joints
Они плоской формы, малоподвижны.The exception is the joint of the thumb. The range of motion of the carpometacarpal joints is no more than 5-10 degrees. They have limited mobility, since the ligaments are well developed. Located on the palmar surface, they form a stable palmar ligamentous apparatus, connecting the bones of the wrist and metacarpal. There are arcuate ligaments on the hand, as well as transverse and radial ones. The capitate bone is central in the ligamentous apparatus, a large number of ligaments are attached to it. Hand palms are much better developed than rear ones. The back ligaments connect the bones of the wrist. They form a thickening of the capsules that cover the joints between these bones. Interosseous located in the second row of wrist bones.
In the thumb carpometacarpal jointformed by the base of the first metacarpal and polygonal bone. The articular surfaces have a saddle shape. This joint can perform the following actions: abduction, adduction, reposition (reverse motion), opposition (opposition) and circulation (circular motion). The volume of grasping movements, due to the fact that the thumb is opposed to all others, increases significantly. 45-60 degrees is the mobility of the carpal-metacarpal joint of this finger during adduction and abduction, and during the reverse movement and contraposition - 35-40.
The structure of the hand: the metacarpophalangeal joints
The named joints of the hand are formed by the heads.metacarpal bones with the participation of the bases of the proximal phalanges of the fingers. They are spherical in shape, have 3 axes of rotation perpendicular to each other, around which extension and flexion, abduction and adduction, as well as circular movements (circulation) are carried out. Adduction and abduction is possible at 45-50 degrees, and flexion and extension - at 90-100. These joints have collateral ligaments located on the sides that strengthen them. Palmar, or accessory, are on the palm side of the capsule. Their fibers are intertwined with the fibers of the deep transverse ligament, which prevents divergence of the heads of the metacarpal bones in different directions.
Interphalangeal joints of the hand
Они блоковидной формы, а оси их вращения проходят transversely. Extension and flexion is possible around these axes. The proximal interphalangeal joints have a volume of flexion and extension equal to 110-120 degrees, distal - 80-90. Interphalangeal joints are very well strengthened due to collateral ligaments.
Synovial as well as fibrous sheaths of the tendons of the fingers
The extensor retainer, as well asflexor retainer plays a huge role in strengthening the position of the tendons of the muscles passing under them. This is especially true when the brush: when it is unbending and flexing. Nature designed a very competent structure of the hand. The tendons are supported in the above-mentioned bundles from their inner surface. Separating the tendons from the bones prevents binding. It allows to withstand a lot of pressure during intensive work and strong muscle contraction.
Уменьшению трения и скольжению сухожилий, идущих on the hand from the forearm, contribute to the special tendon sheaths, which are bone-fibrous or fibrous channels. They have synovial vagina. The largest number of them (6-7) is under the extensor retainer. The radial and ulna bones have grooves that correspond to the location of the tendons of the muscles. And also the so-called fibrous bridges that separate the channels from each other and pass to the bones from the extensor retainer.
Palmar synovial sheaths refer toflexor tendons of the fingers and hands. The common synovial vagina extends to the center of the palm and reaches the distal phalanx of the fifth finger. Here are the tendons of the superficial and deep flexor of the fingers. The thumb has a long flexor tendon located in the synovial vagina apart and passing to the finger along with the tendon. The synovial vaginas in the palm have no tendons of the muscles that go to the fourth, second and third fingers. Only the tendon of the fifth finger has a synovial vagina, which is a continuation of the common.
Muscle brushes
In the figure below you can see the muscles of the arm. The structure of the hand is shown here in more detail.
The muscles in the hand are only on the palmar side. They are divided into three groups: middle, large and small fingers.
Since finger movements require great precision, a significant number of short muscles are found in the hand, which complicates the structure of the arm. The muscles of the arms of each group will be discussed below.
Medium muscle group
It is formed by worm-like muscles, starting fromtendons of the deep flexor of the fingers and attached to the proximal phalanges, or rather their bases, from the second to the fifth finger, if we consider the structure of the hand. The muscles of the arm also come from the back and palmar interosseous, located in the gaps between the bones of the metacarpus, attached to the base of the proximal phalanges. The function of this group is that these muscles are involved in flexing the proximal phalanges of these fingers. Thanks to the palmar interosseous muscles, it is possible to bring the fingers to the middle finger of the hand. With the help of the rear interosseous occurs their breeding to the side.
Thumb muscles
This group forms a thumb elevation.These muscles begin near the adjacent bones of the metacarpus and wrist. As for the thumb, its short flexor is attached near the sesamoid bone, which is located near the base of the proximal phalanx. The opposing thumb muscle goes to the first bone of the metacarpus, and the resulting thumb is located on the side of the inner sesamoid bone.
Small finger muscles
This muscle group forms an elevation on the inside of the palm. These include: the outgoing little finger muscle, opposing the little finger, short palmar, as well as a short flexor.
They originate from nearby bones in the wrist. These muscles are attached to the base of the fifth finger, more precisely, its proximal phalanx, and to the fifth metacarpal bone. Their function is reflected in the title.
In the article we tried to present the most accuratethe structure of the hand. Anatomy is a fundamental science that requires, of course, more careful study. Therefore, some issues remained unlit. The structure of the hand and wrist is a topic that interests not only physicians. Knowledge of it is also necessary for athletes, fitness instructors, students and other categories of people. The structure of the hand, as you have noticed, is rather complicated, and it can be studied for quite a long time from various sources.
